U.S. Pat. No. 4,375,021, in the name of Franco T. Pardini and Francesco DeVizzi, describes the use of a magnetic assembly arranged about the circuit breaker contacts for electrodynamically repulsing the contacts and for electrodynamic motivation of the arcs that occur when the contacts become separated. The arc chute used within the breaker for cooling and extinguishing the arc is formed by enfolding a metal strip partially around an insulating support substrate.
U.S. Pat. Nos. 2,005,684 and 2,551,822 both teach arc chute assemblies that contain a composite structure of one material having good arc resistant properties such as asbestos alongside another material having good physical support properties.
When the Pardini et al. circuit breaker is used to interrupt short circuit current at rated voltages in excess of 400 volts, it has been determined that the arc chute side supports interfere with the arc extinguishing process at the higher arc temperatures and higher arc voltages. Asbestos materials, having excellent high temperature and electrical resistance properties, are no longer available to the electrical industry by legislative mandate.
U.S. patent application (41PR-7577) entitled "Electric Circuit Breaker Arc Chute Composition" describes a two-layer laminate structure for arc plate side supports wherein the layer facing the arc consists of a resin impregnated cloth fiber while the opposite layer consists of a resin-impregnated glass fiber. The opposite layers must be color-coded to insure that the cloth fibers face the arc rather than the glass fibers. Should the glass fibers become subjected to the temperatures generated within the arc chute, the low ionization potential elements within the glass fibers would become ionized and thereby interfere with the arc extinction process.
One purpose of the instant invention accordingly is to provide arc chute side support materials having the necessary thermal and electrical resistant properties while maintaining sufficient physical strength to survive the arc heating effects generated within higher voltage circuits without color-code or other orientation requirements.